1. Field of the Invention
This invention pertains to the field of wheel hubs and axles for motor vehicles. More particularly, the invention pertains to axle seals used to reduce the exposure of contaminants to wheel bearing seals and wheel bearings.
2. Description of the Prior Art
Unitized seals, such as those used with a wheel bearing of a motor vehicle, generally include an outer sleeve and an inner sleeve supported for mutual relative rotation. It has been observed that dust or dirt in contact with the unitized seal may cause accelerated wear. The worn unitized seal does not provide a satisfactory hydraulic seal resulting in axle lubricant leakage and contamination from exterior sources which ultimately leads to customer dissatisfaction.
One attempted solution has been to provide an additional seal to reduce the flow of such contaminants toward the unitized bearing seal. Various designs have been suggested, however none have satisfactorily eliminated or substantially reduced the flow of contaminants toward the unitized bearing seal and wheel bearing. These axle seals employ two separate pieces, utilizing an elastic seal and a rigid sleeve adapted to receive the elastic seal. The elastic seal statically engages the axle, and frictionally rotates within the rigid sleeve, which is installed in a wheel support member, such as a steering knuckle. To prevent damaging the fragile seal during shipment of the axle, it must be separately placed on the axle just prior to installing the axle into the steering knuckle. While this prevents damage to the elastic member during axle shipment, the design is more costly to assemble and since the rigid sleeve must be designed to receive the elastic seal during axle installation, the resulting seal interface allows the passage of contaminants.
It would be desirable to provide an unitary axle seal capable of further reducing the flow of contaminants toward the unitized bearing seal and wheel bearings than heretofore exhibited. Additionally, it would be beneficial to provide a unitary axle seal capable of being installed in a single assembly operation, preferably on a steering knuckle prior to its shipment to a final assembly plant.